1. Field of the Invention
The present invention relates to a cooling apparatus, and more particularly to a cooling apparatus for use in the projection display apparatus.
2. Description of the Related Art
For the high quality images and the convenience of the projection display apparatus, the projection display apparatus is more and more popular in various fields of the whole world. Generally, the 75% heat of the projection display apparatus is from the light lamp and the other 25% is from the power supply unit.
A projection display apparatus 10 of the prior art mainly includes a light lamp 11, an optical engine 12, a power supply unit 13, and a cooling apparatus 14. The cooling apparatus 14 is by means of a fan 141 and a plurality of guiding plate 142A, 142B, and 143C to sequentially guide the cooling airflows provided by the fan 141 to the light lamp 11, the optical engine 12, and the power supply unit 13. The light lamp 11 is far from the fan 141 so the cooling path is too long that causes the cooling energy loss. The optical engine 12 and the power supply unit 13 adjacent to the fan 141 have limited cooling efficiency for the bad design of the guiding plate 142A and 142C. In addition, depending on different standard alternating current which the various countries have, the power devices (such as the resistances, capacitance, diodes, and coils) inside the power supply unit 13 have different power, and produce the more or less heat to cause the devices inside the projection display apparatus to have different temperature so that the projection display apparatus of the prior art, by means of a single cooling apparatus 14, can't reach the best cooling efficiency.
Meanwhile, the projection cooling apparatus of the prior art can't adjust to the input voltage to instantaneously adjust the rotational speed of the fan. Therefore, the prior art apparatus not only can't instantaneously cool the power supply unit 13 but also can't adjust the rotational speed of the fan according to the different standard alternating current or the different environmental temperature to reach the best cooling efficiency.